1. Field of the Invention
The present invention relates to an apparatus for aligning and clamping multiple optical fibers in an electro-optical device. More particularly, the present invention relates to a method and apparatus for quickly and inexpensively aligning an (Mxc3x97N) array of optical fibers into a semiconductor wafer.
2. Description of the Related Art
Multiple channel freespace optical systems require inputs and outputs of optical signals using optical fiber. For systems with small numbers of channels, these fibers can be mechanically routed using v-shaped grooves or other similar mechanisms to hold and align the fibers as a (1xc3x97N) array.
FIG. 1 is a side view of a conventional one-dimensional optical fiber alignment system 100 having a (1xc3x97N) array of optical fibers that are aligned using v-shaped grooves. In this case, a (1xc3x974) array is described. As shown in FIG. 1, a semiconductor wafer 110 has a plurality of v-shaped grooves 113 that each hold a respective one of a plurality of optical fibers 116.
When  less than 100 greater than  oriented crystal silicon is used for the semiconductor wafer 110, v-shaped grooves 113 can be easily formed on a top surface of the wafer 110. Ends of the optical fibers 116 are placed in these grooves 113 so that they can be properly aligned. Once in these grooves 113, the optical fibers 116 can be cut and then potted with a glue to be fixed into place. Then a connecting surface, or end face, of the wafer 110 is polished back to provide each of the optical fibers 116 with a clean connective face. The wafer 110 is then aligned as necessary into an optical system.
However in optical systems with a large channel count, it is often desirable to have more optical fibers aligned than would be practical in a (1xc3x97N) array. Thus, it is necessary in these systems to arrange the fibers into an (Mxc3x97N) array. The conventional alignment system achieves this by stacking M (1xc3x97N) arrays to form an (Mxc3x97N) array.
FIG. 2 is a side view of a conventional multi-dimensional optical fiber alignment system having an (Mxc3x97N) array of optical fibers that are aligned using v-shaped grooves. In this case, a (4xc3x974) array is described, made by stacking four (1xc3x974) arrays on top of each other. As shown in FIG. 2, the multi-dimensional optical fiber alignment system 200 includes a plurality of stacked semiconductor wafers 210, 220, 230, and 240. The wafers have v-grooves on both sides thereof, or some other structure, to align the stack of wafers to each other.
Each of wafers 210, 220, 230, and 240 are formed as shown for the (1xc3x97N) array in FIG. 1, except for also having the alignment grooves on bottom surfaces thereof. As in the semiconductor wafer 110 of FIG. 1, the first semiconductor wafer 210 includes a plurality of first v-shaped grooves 213 that each hold a respective one of a plurality of first optical fibers 216. Similarly, the second wafer 220 includes a plurality of second v-shaped grooves 223 that each hold a respective one of a plurality of second optical fibers 226. The third wafer 230 includes a plurality of third v-shaped grooves 233 that each hold a respective one of a plurality of third optical fibers 236. Also, the fourth wafer 240 includes a plurality of fourth v-shaped grooves 243 that each hold a respective one of a plurality of fourth optical fibers 246. Also, wafers 210, 220 and 230 are shown as including the v-shaped grooves 238 on respective bottom surfaces thereof, which correspond with respective v-shaped grooves on the upper surfaces of the respective stacked wafers.
However, as the (1xc3x97N) arrays are stacked on top of each other, alignment errors between individual wafers rapidly compound, resulting in significant alignment errors. Thus, while the fabrication process of the individual wafers 210, 220, 230, and 240 provides a very good tolerance in the horizontal direction, the stacking process results in a very poor tolerance as the number of stacked wafers increases.
In view of such manufacturing tolerances in the stacking process, special structures and assembly techniques are required to align the array of fibers to the system. However, for multi-channel systems, the use of existing fiber array alignment techniques requires a prohibitively large number of precision alignments per system, as well as numerous fiber holding components to achieve the required level of precision. This can significantly increase fabrication time and cost.
It is therefore desirable to have a system and method for quickly and cheaply aligning large arrays of optical fibers.
The present invention is therefore directed to multiple fiber chip clamp which substantially overcomes one or more of the problems due to the limitations and disadvantages of the related art.
Therefore, a new apparatus and method has been designed that precisely locates and clamps multiple fibers using precision etched silicon wafers or substrates, that eliminates numerous precision alignments, and dramatically reduces the number of components required to clamp the fibers.
An optical fiber clamp of the present invention includes a first wafer having a first surface with a plurality of first holes formed therethrough; and a second wafer having a second surface with a plurality of second holes formed therethrough, the second surface of the second wafer facing the first surface of the first wafer. The first and second wafers are laterally movable with respect to each other to a clamping position whereby an optical fiber placed through a respective pair of the first and second holes is held stationary against sidewalls of the first and second holes.
For example, the first wafer may be stationary and the second wafer may be laterally movable with respect to the first wafer. As such, the sidewalls of each of the second holes of the second wafer may be covered with a compliant material. The compliant material may comprise one of rubber or plastic.
At least one of the first and second holes may be diamond-shaped, triangular-shaped, or rectangular-shaped.
The first wafer should be sufficiently thick such that when the second wafer is at the point of farthest movement, or in other words at the clamping position, the optical fibers in the second holes are pressed along the same sidewall of respective second holes. Alternatively, the second wafer may be sufficiently thick such that when the second wafer is at the point of farthest movement, the optical fibers in the first holes are pressed along the same sidewall of respective first holes.
In an alternative embodiment, an optical fiber clamp of the present invention includes a plurality of wafers each having a plurality of holes formed therethrough, surfaces of the plurality of wafers through which the holes are formed facing each other so that respective holes of the plurality of wafers are aligned. The plurality of wafers are laterally movable with respect to each other to a clamping position whereby an optical fiber placed through respective aligned holes of each of the plurality of wafers is held stationary against sidewalls of the respective aligned holes.
For example, the optical fiber clamp may include three wafers, whereby the middle wafer is laterally movable with respect to the other wafers which are stationary. As such, sidewalls of the holes formed in the middle wafer may be covered with a compliant material. The compliant material may comprise one of rubber or plastic.
The holes of the plurality of wafers may be diamond-shaped, triangular-shaped, or rectangular-shaped.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.